Study shows bandwidth caps create user uncertainty, risky decisions

May 07, 2012

Georgia Tech postdoctoral researcher Marshini Chetty of the School of Interactive Computing has shown that capped broadband service often forces users into risky decisions that could be mitigated by providing them better tools to monitor and manage their home networks. Credit: Georgia Institute of Technology

Recently, many U.S. Internet service providers have fallen in line with their international counterparts in capping monthly residential broadband usage. A new study by a Georgia Tech researcher, conducted during an internship at Microsoft Research, shows such pricing models trigger uneasy user experiences that could be mitigated by better tools to monitor data usage through their home networks.

Home users, the study found, typically manage their capped broadband access against three uncertaintiesinvisible balances, mysterious processes and multiple usersand these uncertainties have predictable impacts on household Internet use and can force difficult choices on users. Given the undeniable trend in both Internet norms (such as cloud-based applications) and home-entertainment delivery toward greater broadband requirements, the study seeks to create awareness and empathy among designers and researchers about the experience of Internet use under bandwidth caps.

Marshini Chetty, a postdoctoral researcher in Georgia Tech's School of Interactive Computing, interviewed 12 households in South Africa, a country in which broadband caps were universal until February 2010. Typically, the caps set by South African ISPs are severe with some plans only offering 1 GB of data per month. At the time of the study, the caps ranged up to 9GB of data, far lower than the 150GB-250GB caps set by U.S. providers.

What Chetty and her collaborators found were coping mechanisms built into South Africans' daily lives in order to manage their online activities under the caps. For example, some would routinely "top up" their accounts (pay additional fees for incremental cap increases), while others would visit family members to use their Internet accounts, or switch from desktop connectivity to smartphones. And with few (if any) ways for customers to monitor Internet usage throughout the month, their access often would be cut off in the middle of performing an online activity.

"People's behavior does change when limits are placed on Internet accessjust like we've seen happen in the smartphone marketand many complain about usage-based billing, but no one has really studied the effects it has on consumer activity," said Chetty, who earned her Ph.D. in computer science from Georgia Tech in 2011. "We would also hear about people 'saving' bandwidth all month and then binge downloading toward the end of their billing period."

"Mysterious processes" refers to customers' inability to determine which applications are eating up their bandwidth, ranging from being unaware that streaming video or downloading songs consumes much more data than normal web browsing, to not knowing that many background applications (such as automatic software updates) count against the monthly cap.

"We were surprised to learn that many of the households we studied chose not to perform regular software updates in order to manage their cap," Chetty said. "This activity can be benign for some applications, inadvisable for others and downright dangerous in certain cases. For example, not installing security patches on your system can leave you vulnerable to viruses and other sorts of cyber attacks." Chetty suggested that the frequency of such risky behaviors among the broader population of metered/capped Internet users should be assessed via follow-up scientifically representative surveys.

Finally, in households with multiple Internet users, it can be difficult for the heads of the household to manage overall activity when they are not fully aware of each member's Internet use. As with other consumable resources in a household, from milk to hot water, the apportionment of "fair" amounts of bandwidth reflects family practices and requires a fair bit of nuance, varying by family style and composition.

"As ISPs move more toward usage-based pricing, we need to keep in mind the reactive behaviors that consumers adopt and the consequences of those behaviors. Because when you have broadband caps, you will use the Internet differently," Chetty said. "This study was performed in South Africa, and although the caps are higher in the United States, there are still instances where people are hitting them. So if you're going to have caps, you should empathize with your users and offer ways for customers to see how their data are being used and who is using them." More tools are becoming available, from ISPs, within operating systems and from third parties; but this is one of the first academic studies that systematically reveals why there is a demand for such tools, and why they are important to users.

The study's findings are summarized in the paper, "'You're Capped!' Understanding the Effects of Bandwidth Caps on Broadband Use in the Home," which Chetty will present on May 10 at the 2012 ACM SIGCHI Conference on Human Factors in Computing Systems (CHI 2012), being held May 5-10 in Austin, Texas. Chetty's coauthors include Beki Grinter, professor in the Georgia Tech School of Interactive Computing, and Richard Banks, A.J. Bernheim Brush and Jonathan Donner from Microsoft Research. The paper is one of nine Georgia Tech entries in the main program of CHI 2012.

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Bandwidth caps are a rip-off policy. Bits on the internet are not like water or electricity. They don't run out. The only reason for metering bandwidth usage is to skim more money off of the customers.

It allows the ISP to upsell more expensive plans for many times the going rate of the artifically limited basic account. It's a perfect example of an artifical scarcity.

Some might argue that bandwidth caps are meant to ease congestion on the network, but that's not really true. It limits how much data people transmit on the whole, but it doesn't change when they do it, so people are still going to log in at lunch break or after work to check the news just the same.

On the internet, when is of the essence, not how much. Bandwidth caps are like giving people monthly driving quotas to help ease rush hour traffic. Everybody still needs to go to work in the morning, so it would just make life more difficult.

May be in the USA but in most other countries it is default. Forein ISPs have to pay for connections to other systems/networks, which is mostly outside their own country (eg, to the USA). If ISP cost is based on volume and if they are paying for every MB the customer sends around, then it is fair for them to calculate user charges on same basis.

But I think the limits of just a few GB per month in this article, is very artificially low (compared to most other countries), so yes, of course there is much more anxiety. Limits of 200GB - 400GB would not produce such big effect.

If ISP cost is based on volume and if they are paying for every MB the customer sends around, then it is fair for them to calculate user charges on same basis.

Except it isn't. It's usually bilateral - you route my traffic and I route yours, because data on the internet goes two ways and nobody can really isolate whose bits they are. For example, if I initiate a download from another ISP's network, I'm sending a small amount of data that way, and recieve a lot of data this way, so technically they're sending stuff to me, so they should pay my ISP for the inbound traffic, or not?

It's the same problem as with data centers. When they first came around, people didn't know how to bill the customers and based on what. Time? Processor cycles? Amount of data to be processed? The most reliable metric ended up being the amount of electricity required to run the air conditioning. Similiarily, ISPs share things like maintenance costs as part of the deals, but they don't pay for data

They also create frustration. I remember back when the bandwidth cap was 2-4Gb by default here and that was considered "unlimited". It used to run out way before the end of the month, before you'd even realized that you've reached the limit. And, before you knew it, you'd receive internet speeds of 56kb/s thanks to greedy service providers. Like I said, it's both a rip-off and frustrating. These days, the caps are much more reasonable and appropriate. At the moment, I have a cap of 100Gb, and, so far, I haven't managed to use it all.

Similiarily, if you have an ISP that is charging another ISP transit fees per megabyte, someone is getting ripped off badly.

Point being that the data traffic between two ISP's networks is mostly symmetrical, so the cost calculated by the amount of data tends to average out to zero, or very close to over the long term. This is true regardless of the size of the two networks.

A note of warning though: bandwidth really refers to speed instead of amount. It's a misnomer to say "a bandwidth of 2 GB". Bandwidth is the size of the channel used for transmission. Not the amount of data transmitted therein.

When ISPs talk of bandwidth among themselves, they're talking about megabytes per second. When they turn to their customers and talk about bandwidth (caps), they talk about megabytes. This semantic difference is used to make it seem like they're short on megabytes to justify the caps, when in reality they're running out of megabytes per second.

It means their infrastructure isn't fast enough to serve all the people they sold it to.

Should an ISP also provide its own "competing" TV service (as many do), I wonder how much effect that has on its capping policy?If I'm getting a stream from some internet site, I'm not watching the advertising-encrusted fare offered via, e.g. some cable TV channel. I assume providers that also offer traditional TV channels derive some revenue from sale of advertisements.

Should an ISP also provide its own "competing" TV service (as many do), I wonder how much effect that has on its capping policy?

Theoretically it should not make any difference.

The reason why many ISPs offer TV service on the side is becuse they started as cable TV and are now using the same cable network to transmit internet data alongside with the TV, or have transitioned to full digital multicasting on the existing cable network. The difference is that cable networks are not topologically optimal for internet because the users are often connected in a long chain and have to share the bandwidth of the same physical cable in a similiar manner to how cellphones have to share the same radio channel and only transmit one at a time.

Different approaches to this sharing exist, and the more the ISP oversells, the more they have to fiddle with bandwidth sharing to make it work fluently, which creates a problem with the 10% of heavy users who have to be throttled somehow.